A Great Hike to a Great Bay, 9/6, 9 a.m.-noon, The Nature Conservancy, new trail, Durham-Great Bay in Newmarket; Restoring Oysters to Great Bay: A Pearl of a Field Trip, 9/6, 10-11:30 a.m., The Nature Conservancy, RSVP, Lori Johnson, lori_johnsontnc.org, 224-5853, ext. 10, free.